General Biology I: Foundational Concepts and Study Guide

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Introduction to Biology

What is Biology?

Biology is the scientific study of life and living organisms. It encompasses a wide range of topics, from the molecular mechanisms within cells to the interactions between organisms and their environments.

Biology investigates the structure, function, growth, origin, evolution, and distribution of living things.
It uses the scientific method to explore questions about life.

Characteristics of Living Things

Organization: Living things are composed of one or more cells, which are considered the basic units of life.
Metabolism: All living things obtain and use energy.
Homeostasis: The ability to maintain a stable internal environment.
Growth and Development: Organisms grow and develop according to specific instructions coded for by their genes.
Reproduction: The ability to produce new individual organisms, either sexually or asexually.
Response to Stimuli: Organisms respond to environmental changes.
Evolutionary Adaptation: Populations of organisms evolve over generations.

Levels of Biological Organization

Biological systems are organized in a hierarchy from the smallest to the largest scale:

Atom
Molecule
Organelle
Cell
Tissue
Organ
Organ System
Organism
Population
Community
Ecosystem
Biosphere

Example: A human (organism) is made up of organ systems, which are made of organs, composed of tissues, which are made of cells, and so on.

The Nature of Science

What is Science?

Science is a systematic approach to understanding the natural world through observation and experimentation.

Scientific Method: Involves making observations, forming hypotheses, conducting experiments, and drawing conclusions.

Scientific Hypothesis vs. Scientific Theory

Hypothesis: A testable, falsifiable statement or prediction about the natural world.
Theory: A well-substantiated explanation of some aspect of the natural world, based on a body of evidence.
Example: The theory of evolution by natural selection is supported by extensive evidence.

Experimental Variables

Independent Variable: The factor that is changed or controlled in an experiment.
Dependent Variable: The factor that is measured or observed.
Controlled Variables: Factors kept constant to ensure a fair test.
Example: In an experiment testing plant growth under different light conditions, the light type is the independent variable, and plant height is the dependent variable.

Chemistry of Life

Elements and Atoms

Element: A substance that cannot be broken down into simpler substances by chemical means.
Most Abundant Elements on Earth: Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Potassium, Magnesium.
Most Abundant Elements in Living Organisms: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Sulfur (CHONPS).

Atomic Number, Atomic Mass, and Isotopes

Atomic Number (Z): Number of protons in the nucleus of an atom.
Atomic Mass/Mass Number (A): Total number of protons and neutrons in the nucleus.
Isotopes: Atoms of the same element with different numbers of neutrons.
Example: Carbon-12 and Carbon-14 are isotopes of carbon.

pH and Acidity

pH is a measure of hydrogen ion concentration in a solution.
pH scale ranges from 0 (most acidic) to 14 (most basic), with 7 being neutral.
Equation:

Polar vs. Non-Polar Molecules

Polar Molecules: Have unequal sharing of electrons, resulting in partial charges (e.g., water).
Non-Polar Molecules: Have equal sharing of electrons, no partial charges (e.g., methane).
How to Recognize: Look for differences in electronegativity and molecular symmetry.

Biomolecules

Carbohydrates

Definition: Organic molecules composed of carbon, hydrogen, and oxygen (typically in a 1:2:1 ratio).
Monomers: Monosaccharides (e.g., glucose).
Storage Forms: Glycogen in animals, starch in plants.

Proteins

Amino Acids: Building blocks of proteins, each with a central carbon, amino group, carboxyl group, hydrogen, and R group.
Levels of Protein Structure:

Level	Description
Primary	Sequence of amino acids
Secondary	Alpha helices and beta sheets formed by hydrogen bonding
Tertiary	Three-dimensional folding due to side chain interactions
Quaternary	Association of multiple polypeptide chains

Bonds Between Macromolecules: Peptide bonds (proteins), glycosidic bonds (carbohydrates), phosphodiester bonds (nucleic acids), ester bonds (lipids).

Enzymes

Definition: Biological catalysts that speed up chemical reactions without being consumed.
Example: Amylase breaks down starch into sugars.

Lipids

Saturated Fats: No double bonds between carbon atoms; solid at room temperature.
Unsaturated Fats: One or more double bonds; liquid at room temperature.

Dehydration vs. Hydrolysis

Dehydration Synthesis: Joins monomers by removing a water molecule.
Hydrolysis: Breaks polymers into monomers by adding water.

Nucleic Acids: DNA vs. RNA

DNA: Double-stranded, deoxyribose sugar, bases A, T, C, G.
RNA: Single-stranded, ribose sugar, bases A, U, C, G.
Monomers: Nucleotides.

Genetics

Genes and Mutations

Gene: A segment of DNA that codes for a protein or functional RNA.
Mutations: Changes in DNA sequence that can cause diseases (e.g., sickle cell anemia, cystic fibrosis).

Classification and Taxonomy

Taxonomy vs. Systematics

Taxonomy: The science of naming, describing, and classifying organisms.
Systematics: The study of evolutionary relationships among organisms.

Levels of Classification

Level	Example (Human)
Domain	Eukarya
Kingdom	Animalia
Phylum	Chordata
Class	Mammalia
Order	Primates
Family	Hominidae
Genus	Homo
Species	Homo sapiens

Experimental Design and Data Analysis

Understanding Variables and Significance

Be able to identify independent, dependent, and controlled variables in an experiment.
Assess whether observed differences (e.g., a 5-second difference) are statistically significant, often using statistical tests (e.g., t-test).
Significance: A result is significant if it is unlikely to have occurred by chance (commonly, p < 0.05).

Example: If two groups of plants grow for 20 and 25 seconds, statistical analysis is needed to determine if the 5-second difference is meaningful.

Additional info: This guide covers foundational concepts in biology, chemistry of life, biomolecules, genetics, taxonomy, and experimental design, as outlined in the study guide. Students should refer to their syllabus and lectures for more detailed coverage of each topic.